Synopsis At about 2345 local time, 01 June 2000, while loading a cargo of aggregates at Bruce Mines, Ontario, the hull of the Canadian bulk carrier Algowood buckled in way of hold No3. The vessel flooded, sat on the bottom alongside the dock, and was later salvaged and towed to dry dock for repairs. Ce rapport est galement disponible en franais. 1.1 Particulars of the Vessel 1.1.2 Description of the Vessel 1.1.3 Certification of the Vessel 1.2 History of Events 1.3 Certification of Personnel 1.4 Loading Summary 1.5 Condition of the Bottom Alongside the Berth 1.6 Injuries to Persons 1.7 Damage Surveys at Bruce Mines 1.8 Damage Survey in Dry Dock 1.9 Shell Plating Thickness Gauging, Laboratory Testing, and Hull Stresses 1.10 Vessel Strength and Stability 1.11 Loading Sequence 1.12 Cargo Watch Schedules 1.13 Previous Safety Recommendations Regarding Bulk Carriers 1.14 Loading Plan and Operating Procedures 1.1 Particulars of the Vessel 1.1.2 Description of the Vessel 1.1.3 Certification of the Vessel 1.2 History of Events 1.3 Certification of Personnel 1.4 Loading Summary 1.5 Condition of the Bottom Alongside the Berth 1.6 Injuries to Persons 1.7 Damage Surveys at Bruce Mines 1.8 Damage Survey in Dry Dock 1.9 Shell Plating Thickness Gauging, Laboratory Testing, and Hull Stresses 1.10 Vessel Strength and Stability 1.11 Loading Sequence 1.12 Cargo Watch Schedules 1.13 Previous Safety Recommendations Regarding Bulk Carriers 1.14 Loading Plan and Operating Procedures 2.1 General Communications 2.2 Communications and Coordination - Loading/Deballasting 2.3 Loading and Deballasting 2.4 Determination of Draughts 2.5 Condition of the Bottom Alongside the Berth 2.6 Officers' Knowledge of Structural Stresses 2.7 Existing Safety Measures for Bulk Carriers 2.1 General Communications 2.2 Communications and Coordination - Loading/Deballasting 2.3 Loading and Deballasting 2.4 Determination of Draughts 2.5 Condition of the Bottom Alongside the Berth 2.6 Officers' Knowledge of Structural Stresses 2.7 Existing Safety Measures for Bulk Carriers 3.1 Findings as to Causes and Contributing Factors 3.2 Findings as to Risk 3.3 Other Findings 3.1 Findings as to Causes and Contributing Factors 3.2 Findings as to Risk 3.3 Other Findings 4.1 Action Taken 4.2 Safety Action Required 4.1 Action Taken 4.2 Safety Action Required 1.0 Factual Information 1.1 Particulars of the Vessel 1.1.2 Description of the Vessel The Algowood is a self-unloading bulk carrier of all-welded steel construction, with five cargo holds. The propelling machinery, steering gear, wheelhouse, life-saving equipment, and all crew accommodation are located at the after end of the vessel. The location of cargo holds and water ballast tanks are shown in Figure 1. The hull is subdivided by transverse watertight bulkheads: a collision bulkhead, a bulkhead at the after end of the cargo space, and a bulkhead at the after end of the engine room. To unload the vessel, gates at the bottom of the five hopper-shaped holds are opened. This allows cargo to fall onto two fore-and-aft conveyor belts which transport the cargo to the transfer-and-loop belt system at the after end of the cargo space. It is then raised by the loop belt system to an above-deck unloading boom for discharge over the side. The area where the belts run under the cargo holds and the space at the after end which houses the loop belt are referred to as the tunnel and the loop belt casing, respectively. 1.1.3 Certification of the Vessel The Algowood was inspected by Transport Canada Marine Safety (TCMS) ship surveyors on 27March2000 in Hamilton, Ontario. A ship inspection certificate (SIC 11) was issued on 27March2000, valid until 26March2001. The ship was also issued with a Load Line Certificate, Great Lakes and Inland Waters of Canada, valid until 31March2002. Figure1. General Arrangement Outline, M.V.Algowood 1.2 History of Events The Algowood arrived at Bruce Mines, Ontario, at 1755 eastern daylight time on 01June2000 and commenced loading aggregates and manufactured sand at 1813, in accordance with an intended loading/deballasting plan. Except for times required for shifting the vessel in way of the loading structure and brief equipment maintenance periods, loading continued until 2345 the same day. On its arrival at Bruce Mines, the vessel was in a ballast condition, with all cargo holds empty. Port ballast tank No3 was pumped for nine minutes as a counter balance to the vessel's unloading boom, the discharge end of which was slowly moving out over the starboard side of the vessel to allow loading into No5 cargo hold. The deck officer (first mate) in charge (OIC), responsible for deballasting and loading, indicated that the forepeak ballast tank had been previously pumped out to a sounding of approximately 12inches. Port and starboard (PS) No5 ballast tanks, which were not fully pressed up, were being pumped as of 1805. At 1813, the vessel was ready to load into cargo hold No5, hatches nos21, 19, and20, respectively. Loading started at 1823. As of 1843, P S ballast tanks No4 were being discharged. At 2035, loading of cargo in hold No5 was completed with 5700tons of sand (see table in section1.4). The draught aft was reported to be 6.553metres (21feet6inches). As of 1952, pumping of No3 P S ballast tanks recommenced and was suspended at 2010. At 2032, No3 P S ballast tanks were pumped again, this time to completion at 2145. According to the loading plan, the after draught of the vessel was near the maximum allowable of 6.858metres (22feet6inches). At this time, the OIC deviated from the loading sequence and directed the shore rig loader to load HL1 aggregates into hatch No9 instead of hatch No13. The shore rig loader, who was provided with a copy of the intended loading plan for clarification, questioned and acknowledged the sudden change to the loading plan. Loading into hatch No9 commenced at 2044. Pumping of No2 and No1 PS ballast tanks started at 2111 and 2130 respectively. By 2126, 1756 tons of cargo had been loaded into cargo hold No3. Starboard ballast tank No3 was completely pumped out between 2032 and 2145. At this time, the vessel had reached the maximum draught aft and shifting of the vessel aft began. The vessel came to a sudden and abrupt stop, indicating that after end of the vessel might have touched bottom near the end of the slip. The loading rig was just able to reach into hatch No2 of cargo hold No1, in which loading commenced at 2132. While loading hatch No2, the vessel trimmed2 forward and the draught aft was reduced. The OIC shifted the vessel further aft so that the loading rig could begin loading into hatch No1. At approximately 2145, the master returned to the ship and inquired briefly about the vessel's condition of loading with the OIC, after which he proceeded to his cabin. At 2202, pumping of P S ballast tanks Nos1 and2 was stopped. Ballast tanks No1 P S were pumped again from 2240 to 2242. Pumping of No2 PS ballast tanks resumed at 2242 and finished at 2315. Reading draughts in the dark was difficult at this time because visibility was further reduced in rain showers. The after draught was 6.477metres (21feet3inches) at this time and was decreasing as loading forward continued. At 2242, pumping of P S ballast tanks No2 resumed. The loading of cargo hold No1 was almost completed, with an additional 1800tons loaded through hatches nos1, 2, and3 at 2322. Draughts at this point were 6.096metres (20feet) aft, 4.801metres (15feet9inches) at midship, and 3.962metres (13feet) forward; according to the OIC, the vessel was hogged3 by approximately 0.229metre (9inches). The rig operator indicated that there would be a shut down for minor repairs. At 2315, P S ballast tanks No2 were pumped out. At 2345, while continuing to load into hatch No3 of cargo hold No1, the ship made a very loud wrenching sound and buckled4 between hatches nos13 and14, in way of the transverse bulkhead, between frames117 and119. Loading was stopped and the general alarm sounded. At 0010, all crew members were evacuated to shore with the exception of the master and the chief engineer. An initial survey revealed no major pollution. However, an oil boom was deployed to contain some minor hydraulic oil leaks. The forefoot5 and stern section of the vessel struck the ground; subsequently, the hull settled on the bottom. All cargo holds of the vessel were progressively flooded through the tunnel. Concurrent damage to the ballast suction piping led to flooding of the water ballast tanks forward of the structural damage. As flooding progressed, the vessel settled on the bottom with the hull immersed at 8.2metres (26feet11inches) forward and 8.1metres (26feet7inches) aft. Flooding extended from the collision bulkhead to the forward bulkhead of the engine room. In the days following the occurrence, salvage operations were monitored by Lloyd's Register of Shipping, the Salvage Association, and TCMS. Temporary repairs included substantial steel bracing welded to the outside of the shell plating spanning the hull damage. Cargo was unloaded from the holds and diesel oil was discharged. On 10July2000, the vessel was towed to the dry docks at Port Weller, Ontario, for a detailed damage survey, repairs, and reconstruction. 1.3 Certification of Personnel The master and officers held certificates valid for their positions and for the trade in which the vessel was engaged. The master held a certificate for master, local voyage, issued in 1979. The first mate held a certificate for master, local voyage, issued in 1999. The most recent continued proficiency endorsement for both individuals was acquired in 1999. 1.4 Loading Summary The following table includes the best estimates of cargo quantities loaded into each hold at the time of the occurrence. Quantities are rounded to the nearest ton. Water ballast on board the vessel on 01June2000, at the time of the occurrence, totalled approximately 31.8tons. All ballast tanks were sequentially pumped, leaving 11.8tons in the forepeak and 20tons in the afterpeak. 1.5 Condition of the Bottom Alongside the Berth Once the Algowood was removed from the loading berth, an underwater survey of Bruce Mines harbour found that there was no obstruction along the line of dolphins used for berthing. The maximum after draught allowable was 6.858metres (22feet6inches) because of the lake's low water level at that time and the presence of a shallow area in the approach channel. 1.6 Injuries to Persons 1.7 Damage Surveys at Bruce Mines The Algowood experienced a sudden, major structural hull failure, the location, nature, and extent of which are shown in figures3and4 and photographs1, 2, and3. Damage surveys, carried out when the vessel was alongside at Bruce Mines, revealed extensive buckling and distortion on the deck (seeFigure4) above waterline P S shell plating with localised buckling and tensile fracturing of the side shell and of the P S ballast tank hopper6 side. Figure3. Location and extent of initial hull damage 1.8 Damage Survey in Dry Dock Photo1. Starboard side of damaged vessel showing longitudinal deflection of hull 1.9 Shell Plating Thickness Gauging, Laboratory Testing, and Hull Stresses Photograph2. Buckling and fractures on starboard side On 18 July 2000, while the vessel was in dry dock for a damage survey and before the start of permanent repairs, material thickness was gauged ultrasonically by the TSB and shipyard personnel to determine the current thicknesses of principal structural members in the frame spaces immediately forward and abaft the major hull failure. This survey included measurements taken in a band around the vessel in way of frames 117 to 119. Gauge readings at each of these locations generally showed wastage of 1 to 7percent in the shell, bilge, keel, and bottom structural members. There was a mean thickness reduction of some 13percent in way of the tank top plating. None of the recorded material thickness wastage readings exceeded accepted limits at which replacement of the material would be required. During this survey, steel sample specimens were cut out from the keel plate, bottom shell, turn-of-bilge plating, and tank top adjacent to the hull failure, and forwarded to the TSB Engineering Laboratory to identify and determine the current chemical and mechanical characteristics of the steel used in construction of the Algowood. Laboratory examination identified the material as steel, having no abnormalities to adversely affect weldability and having tensile properties and notch-toughness9 characteristics comparable to those of Lloyd's Grade A steel. Photo3. Buckling and fractures on the port side Photo4. Fracture damage to bottom plating in way of the transverse bulkhead between frames 117 and 119 Post-occurrence calculations of the still water bending moment10,11 (SWBM), imposed on the Algowood when partially loaded at Bruce Mines, were made to determine the magnitude and nature of bending stresses12 incurred by the steel structure in way of the hull failure. These calculations confirmed that, immediately before hull failure, the vessel was subjected to a hogging/bending moment about 2.3 times the maximum permissible (sea going). A hogging/ bending moment puts the main deck plating in tension and the bottom structure in compression. The hogging condition, induced at the time of the occurrence, was due to the excess of weight over buoyant support at the ends of the vessel. 1.10 Vessel Strength and Stability The Algowood complied with regulatory requirements and the classification society's structural and longitudinal strength requirements. The Trim and Stability Book with Loading Calculations was approved by TCMS and Lloyd's Register of Shipping. The booklet included information for the master's guidance on the amount of cargo to be loaded into each hold to obtain a desired draught with acceptable shear forces and bending moments for each loading condition. This booklet contains 20 representative loading conditions but does not outline loading and deballasting sequences. The Lloyd's Register of Shipping approved copy was on board at the time of the occurrence. The Algowood was subject to the requirements of the Load Line Regulations (Inland), which state that the master of every ship shall be supplied with sufficient information, in an approved form, to enable him to arrange for the loading and ballasting of his ship in such a way as to avoid the creation of unacceptable stresses in the ship's structure. 1.11 Loading Sequence The ship's personnel generally supervised loading operations in accordance with the routines established by experience on this and other Great Lakes bulk carriers. Adopted cargo loading and unloading sequences depend on the configuration of different ports and their discharge facilities. The sequence also varies with the type and deadweight of each cargo. This plan is prepared before arrival at the loading ports and indicates the vessel's draughts, hatch numbers, cargo, weight, and instructions regarding ballast pumping sequence. In this instance, the loading plan, prepared by the OIC using a personal computer not programmed as a loading instrument, was approved by the master and was also to be used in coordination with the terminal operators. The cargo loading and deballasting sequences were not carried out according to the agreed upon plan. This is due in part to the fact that, at a point in the loading, the vessel could not be moved further astern in the limited depth of water available near the northern extremity of the slip until the aft draught was decreased. Verbal communication was used to enable the OIC to confirm and validate the actual pumping performed by engine room staff. Ballast tank water levels would be confirmed later by tank soundings from deck level. Because a record of tank soundings while deballasting was not kept in the deck log book, it was difficult to coordinate pumping of tanks. It was not possible to confirm the sequence for deballasting, especially when deviations to the plan took place. 1.12 Cargo Watch Schedules The second mate and first mate stood their normal 1200 to 1600 and 1600 to 2000 watches, respectively. Between watches, each had eight hours off, which included several hours of rest. Consequently, fatigue is not considered to have been a contributing factor in this occurrence. 1.13 Previous Safety Recommendations Regarding Bulk Carriers The Department of Transport require that masters on all Canadian bulk carriers be provided with comprehensive written loading and unloading guidance, including the maintenance of a Cargo Book, to ensure that maximum allowable hull girder stresses are not exceeded. Transport Canada (TC) accepted the recommendation. In response to it and associated correspondence, TC advised that the Canadian Code of Safe Practice for Solid Bulk Cargoes (TP 5761) would be revised to reflect the latest International Maritime Organization (IMO) requirements. On 17July1995, Ship Safety Bulletin (SSB) NO13/95 was issued by TC, warning that improper practices and procedures during cargo handling operations was a major cause of extensive structural overstressing damage. A copy of IMO circular MSC 690 was attached to the bulletin. On 26October1998, SSB 13/98 was issued, which included the Code of Practice for the Safe Loading and Unloading of Bulk Carriers. Further attention was drawn to the new International Convention for the Safety of Life at Sea (SOLAS) chapter VI amendments on carriage of cargoes, in particular Regulation 7 that came into force internationally on 01July1998. The regulation requires ships to be provided with a booklet that specifies maximum permissible forces and moments on the ship's hull during loading, unloading, and the voyage. TCMS has also published SSB 07/1996 and 15/1999 to give wide distribution to the issue of bulk carrier safety. It was recommended that all parties involved in loading and unloading bulk cargoes take the Code of Practice for the Safe Loading and Unloading of Bulk Carriers into consideration, become fully familiar with and include the use of these procedures in their operations. Following the damage to the S.S. Beechglen, the owners revised their procedure manuals to require ships' crews to monitor ballasting and deballasting during all loading and unloading operations and to record such operations in a permanent record book, kept in both the engine room and on the bridge. In addition, at the change of watch, the officer being relieved is required to instruct the relieving officer as to the state of the ballast tanks. In a TSB report on the break up and sinking of the bulk carrier Flare (TSB Report M98N0001), the Board was concerned that mariners may not fully appreciate that deviation from approved loading manuals may overstress the structure and lead to catastrophic failures. The Board recommended that: The Department of Transport, in coordination with international agencies (including the International Maritime Organization and the International Association of Classification Societies), bring the need for stricter adherence to approved loading manuals to the attention of shipowners, ship operators and ship masters in order to avoid undue structural stresses in bulk carriers. Transport Canada accepted the recommendation. In response, TC advised that the matter will be brought to the attention of future Port State Control (PSC) meetings to ensure that signing member states to the Paris and Tokyo memoranda of understanding on PSC are aware of and understand the importance of ensuring compliance during PSC inspections. TC has also advised that the matter has been brought to the attention of IMO and TCMS will continue its participation in Working Groups on Bulk Carrier Safety at IMO. The Dangerous Goods, Solid Cargoes Containers (DSC) Subcommittee is developing a manual on Loading and Unloading of Solid Bulk Cargoes for Terminal Representatives. 1.14 Loading Plan and Operating Procedures At the time of the occurrence, the Trim and Stability Book with Loading Calculations, including longitudinal strength data such as SWBM, was aboard for the guidance of ship personnel. This copy was approved by Lloyd's on 22February1982 and contains 20 representative loading conditions. The Notes for the Master state that this book is for information and that it must be considered as such at all times. It is general practice for the first mate to prepare a loading plan and present it to the master for approval. Details and calculations for the loading plan are based on the knowledge and experience of both first mate and master, combined with past loading/unloading data for the vessel. The first mate had the option of using either a form prepared by the Marine Division of Algoma Central Railway (Form 226, Vessel Loading Plan) or a computer spreadsheet using the vessel's onboard computer. Both methods ask for a description of the vessel, cargo weight and location, draughts and ballast, and loading time. However, neither includes information or makes calculations of the hull girder longitudinal strength, shear forces, and bending moments relative to the maximum SWBM approved by Lloyd's. Post-occurrence calculations of the SWBM imposed on the Algowood, when loaded according to the intended loading plan, were made to determine the magnitude and nature of the related bending stresses. These calculations indicate that the vessel would have been subjected to a hogging/bending moment about 1.9 times the maximum permissible bending moment approved by Lloyd's. Adoption of similar loading cargo distribution in previous voyages would lead to fatigue in the hull structure. Canadian regulations do not currently require that vessels of this class carry written guidance on cargo loading or unloading sequences. The company's Safety Management System Manual, which was on board the vessel at the time of the occurrence, contains a section entitled Cargo Procedures. The manual refers to loading and unloading sequences, responsibilities, preparations for loading, loading, deballasting, preparations for unloading, unloading, ballasting, special precautions, and draught survey procedures. Longitudinal stresses and loading procedures are addressed as follows: In preparing the load plan, the following must be taken into consideration: ...minimizing bulkhead, tank top, and longitudinal stresses during loading and deballasting processes. The cargo stowage in each compartment must be monitored frequently to ensure even distribution, having due regard for the avoidance of excessive list, load on the tank tops, and load against bulkheads.